This project encompasses studies aimed at analyzing the participation of macrophages and their products in processes which affect the eye or other tissues. Noteworthy findings: (1) "Activated" macrophages, which are a major component of chronic inflammation, affect normal cells by inhibiting their metabolism ("cytostasis"), whereas cells with malignant properties are killed and lysed by these macrophages ("cytolysis"). A comparison was made between the two macrophage effects using cell lines of lens epithelium. Anti-inflammatory drugs such as indomethacin inhibited the cytostasis but not the cytolysis. Further, prostaglandins, which mediated and enhanced cytostasis, suppressed the cytolytic process. These findings indicate that cytostasis and cytolysis are brought about by different sets of biochemical reactions. (2) A macrophage product, interleukin-1 (IL-1), plays a major role in mediating certain immune responses, inflammatory processes and wound healing. The pattern of production and release of IL-1 by human monocytes was further examined. A direct relationship was found between the damaging capacity of added agents and the levels of IL-1 production, suggesting that IL-1 serves as a mediator for the body's response to injury. Another finding concerns monocytes' loss of capacity to produce IL-1 following preincubation in culture for more than 24 hours. Also of note is the finding of marked differences between the molecular species which make the extracellular and intracellular pools of human monocyte IL-1. The released activity consists of a single small-sized molecular species, whereas the intracellular pool comprises at least four molecular species of a wide range of size. The studies on the IL-1 system thus further extend knowledge of the unique features of this mediator.